Circuit/System Description

The fuel level sensor changes resistance based on fuel level and is wired to the K111 Fuel Pump Power Control Module. The K111 Fuel Pump Power Control Module sends the fuel level sensor reading to the Engine Control Module (ECM) via serial data. The ECM monitors the fuel level sensor signal in order to determine the fuel level. When the fuel tank is full, the resistance of the fuel level sensor is low. When the fuel tank is empty, the resistance of the fuel level sensor is high. The ECM uses the signal voltage of the fuel level sensor to calculate the percentage of remaining fuel in the tank. The ECM sends the fuel level percentage via serial data to the body control module (BCM). The BCM then sends the fuel level percentage via serial data to the P16 Instrument Panel Cluster Control Module to control the fuel gauge.

In order to reduce false fuel level readings due to variations such as fuel slosh, the displayed fuel level is a buffered value. Therefore, increases or decreases in actual fuel level may take several minutes to change the gauge position, especially if the fuel level change occurs while the ignition is ON. Also, due to irregular fuel tank shapes and fuel level sensor arm travel limitations, the fuel gauge may display FULL even after several gallons of fuel have been used since the tank was filled. This can be especially apparent if the tank is over-filled, as it would require more fuel be used before the level gets low enough to allow the fuel sensor arm to start to move again. This is a normal characteristic, and no repairs should be attempted.